// undine docs
Objects
The Objects tab is where Blender scene objects become part of an Undine simulation.
Before the solver can run, the relevant objects need a role: domain, emitter, or collider.
Tagged scene roles
The panel shows the active object and the current role state for the scene.
The Tagged in Scene line summarizes how many objects are currently tagged as domains, emitters, and colliders.
| UI element | Purpose | Notes |
|---|---|---|
| Domain object field | Shows the object currently assigned as the simulation domain. | The screenshots show Domain: Cube as the active domain assignment. |
| Emitter object field | Shows or selects an emitter object for the current setup. | Emitter objects define where liquid particles enter or initially occupy the simulation. |
| Add / Volume | Associates the selected volume-style source with the emitter setup. | Use this when the emitter should be interpreted as a volume source rather than only as a surface or point source. |
| Tagged in Scene | Counts the current Domain, Emitter, and Collider roles. | Use this as a quick validation pass before pressing Run. |
| Active Object Params | Displays parameters for the selected object role. | If Role is NONE, tag the object before expecting solver parameters to appear. |
Role buttons
The role buttons write Undine metadata to the selected Blender object.
Changing the active object in Blender changes which object the buttons operate on.
| Button | Effect | Typical use |
|---|---|---|
| Tag Domain | Marks the selected object as the simulation domain. | Use on the container or bounds object that defines the simulation space. |
| Tag Emitter | Marks the selected object as a fluid emitter. | Use on objects that create or contain liquid particles. |
| Tag Collider | Marks the selected object as a collider. | Use on obstacles, characters, moving geometry, or containers that should push back on the liquid. |
| Clear Tags | Removes Undine role assignments from the tagged setup. | Use when rebuilding a scene setup or correcting accidental role assignment. |
Active Object Params
Active Object Params is role-sensitive. Domain, emitter, and collider objects can expose different controls because they contribute to different solver stages.
When the selected object is shown as Role: NONE, the panel intentionally does not expose solver parameters. Tag the object first, then return to the active object parameters.
Practical checks
- Confirm there is exactly one intended domain unless a multi-domain workflow is explicitly supported by the current build.
- Confirm emitters are inside or intersect the domain volume.
- Confirm colliders that should affect the liquid are tagged before baking animated colliders.
- Use the scene counts to catch missing emitters or accidental collider tags early.